We present a bulk micromachining technology, based on vertical trench isolation, for fabrication of two-level MEMS in a standard monocrystalline silicon substrate. The technology, suitable for full integration with on-chip electronics, employs double-side processing to obtain functional micromechanical structures on both sides of the substrate. Etching and release of these microstructures are performed in a single plasma chamber allowing dry, low temperature processing. Utilizing double-side processing, high-aspect-ratio monocrystalline MEMS with integrated vertical electrical insulation on fixed and even on movable parts are fabricated on one side of the wafer and, at the same time, mechanically and electrically coupled with released micromechanical structures on the opposite side. This opens new design opportunities to improve performance and functionality of MEMS devices. The presented technology is employed for fabrication of electrostatic XY-scanners for probe-based data storage with a significantly larger effective recording area proving the feasibility and large potential of this technology.